/*
 * Copyright (C) 2007 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import javax.annotation.Nullable;

import com.google.common.annotations.GwtCompatible;

/**
 * Factory and utilities pertaining to the {@code MapConstraint} interface.
 * 
 * @author Mike Bostock
 */
@GwtCompatible
class ConstrainedMap<K, V> extends ForwardingMap<K, V> {
    final Map<K, V> delegate;
    final MapConstraint<? super K, ? super V> constraint;
    private volatile Set<Entry<K, V>> entrySet;

    ConstrainedMap(Map<K, V> delegate,
            MapConstraint<? super K, ? super V> constraint) {
        this.delegate = checkNotNull(delegate);
        this.constraint = checkNotNull(constraint);
    }

    @Override
    protected Map<K, V> delegate() {
        return delegate;
    }

    @Override
    public Set<Entry<K, V>> entrySet() {
        if (entrySet == null) {
            entrySet = constrainedEntrySet(delegate.entrySet(), constraint);
        }
        return entrySet;
    }

    @Override
    public V put(K key, V value) {
        constraint.checkKeyValue(key, value);
        return delegate.put(key, value);
    }

    @Override
    public void putAll(Map<? extends K, ? extends V> map) {
        for (Entry<? extends K, ? extends V> entry : map.entrySet()) {
            put(entry.getKey(), entry.getValue());
        }
    }

    private static <K, V> Entry<K, V> constrainedEntry(final Entry<K, V> entry,
            final MapConstraint<? super K, ? super V> constraint) {
        checkNotNull(entry);
        checkNotNull(constraint);
        return new ForwardingMapEntry<K, V>() {
            @Override
            protected Entry<K, V> delegate() {
                return entry;
            }

            @Override
            public V setValue(V value) {
                constraint.checkKeyValue(getKey(), value);
                return entry.setValue(value);
            }
        };
    }

    private static <K, V> Set<Entry<K, V>> constrainedEntrySet(
            Set<Entry<K, V>> entries,
            MapConstraint<? super K, ? super V> constraint) {
        return new ConstrainedEntrySet<K, V>(entries, constraint);
    }

    private static class ConstrainedEntries<K, V> extends
            ForwardingCollection<Entry<K, V>> {
        final MapConstraint<? super K, ? super V> constraint;
        final Collection<Entry<K, V>> entries;

        ConstrainedEntries(Collection<Entry<K, V>> entries,
                MapConstraint<? super K, ? super V> constraint) {
            this.entries = entries;
            this.constraint = constraint;
        }

        @Override
        protected Collection<Entry<K, V>> delegate() {
            return entries;
        }

        @Override
        public Iterator<Entry<K, V>> iterator() {
            final Iterator<Entry<K, V>> iterator = entries.iterator();
            return new ForwardingIterator<Entry<K, V>>() {
                @Override
                public Entry<K, V> next() {
                    return constrainedEntry(iterator.next(), constraint);
                }

                @Override
                protected Iterator<Entry<K, V>> delegate() {
                    return iterator;
                }
            };
        }

        // See Collections.CheckedMap.CheckedEntrySet for details on attacks.

        @Override
        public Object[] toArray() {
            return ObjectArrays.toArrayImpl(this);
        }

        @Override
        public <T> T[] toArray(T[] array) {
            return ObjectArrays.toArrayImpl(this, array);
        }

        @Override
        public boolean contains(Object o) {
            return Maps.containsEntryImpl(delegate(), o);
        }

        @Override
        public boolean containsAll(Collection<?> c) {
            return Collections2.containsAll(this, c);
        }

        @Override
        public boolean remove(Object o) {
            return Maps.removeEntryImpl(delegate(), o);
        }

        @Override
        public boolean removeAll(Collection<?> c) {
            return Iterators.removeAll(iterator(), c);
        }

        @Override
        public boolean retainAll(Collection<?> c) {
            return Iterators.retainAll(iterator(), c);
        }
    }

    static class ConstrainedEntrySet<K, V> extends ConstrainedEntries<K, V>
            implements Set<Entry<K, V>> {
        ConstrainedEntrySet(Set<Entry<K, V>> entries,
                MapConstraint<? super K, ? super V> constraint) {
            super(entries, constraint);
        }

        // See Collections.CheckedMap.CheckedEntrySet for details on attacks.

        @Override
        public boolean equals(@Nullable Object object) {
            return Collections2.setEquals(this, object);
        }

        @Override
        public int hashCode() {
            return Sets.hashCodeImpl(this);
        }
    }
}
